The prior art indicates that Guinea pigs with transplanted hepatocellular carcinoma (Line 10) in their skin and metastases in their regional lymph nodes can be cured by the intralesional injection of living BCG (see Zbar et al., Science 172 (1971) 271-3). Killed BCG or BCG cell walls suspended in saline are not therapeutic in this system. Cures comparable to those produced by living BCG have been produced by the intralesional injection of BCG cell wall fragments attached to mineral oil which was emulsified in an aqueous solution of saline containing Tween 80. One of the components of the mycobacterial cell wall is cord factor (trehalose-6,6-dimycolate), (see Lederer, Pure Appl. Chem.25 (1971) 135-150), a compound which possesses some of the biological properties of living BCG. Cord factor suppresses the development of urethane induced tumors in the lungs of mice to an extent similar to that produced by living BCG (Bekierkunst, A., et al. Science 174 (1971) 1270. It was found that a mixture of delipidated and deproteinized cell walls from Mycobacterium tuberculosis H37 Ra suspended in 1.25% mineral oil emulsion cured established tumours in the skin after intratumoural administration in 33% of the cases. This was increased to 83% when a mixture of cord factor and delipidated cell walls was used (Bekierkunst A. et al, Infection and Immunity, 10 (1974) 1044).
A similar percentage of cures was obtained with heat-killed BCG cells coated with cord factor. This compares favorably with the rate of cure achieved with living BCG cells (about 60%). A vaccine containing dead BCG and living tumor cells prevented the growth of tumor cells introduced distally into the skin of guinea pigs at the time of vaccination. The efficacy of the vaccination was substantially increased when cord factor was included in the vaccine (Bekierhunst A., Int. J. Cancer, 16 (1975) 442).